If you want a Pokémon fan game with a native speed-up button (usually Q or Tab), consider trying Pokémon Reborn (with mods), Pokémon Rejuvenation , or Pokémon Infinite Fusion .
As of my knowledge cutoff in October 2023, Pokémon Solar Light & Lunar Dark — a well-known fan-made RPG Maker game — does have an official built-in speed-up button** like you'd find in many modern Pokémon fan games (e.g., Pokémon Infinite Fusion or Pokémon Reborn with the Speed-Up mod). pokemon solar light and lunar dark speed up button